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FIELD
TESTING FOR LEAD AND HEAVY METALS IN SOIL WITH XRF |
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- TOPICS
The
Advantages of Field Screening with XRF
Quality
Assurance Methods
Table 1:
Comparing XRF Field Data to Laboratory Results
Services
Available in Other States
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- Gray Environmental, Inc. offers
non-destructive, field-based measurement of metals in soil
utilizing a Thermo-NITON x-ray
fluorescence instrument.
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APPLICATIONS
WHERE WE HAVE UTILIZED XRF FOR SOIL:
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Brownfields
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Harbors
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Industrial Properties
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Military Bases
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Shooting
Ranges
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Residential
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Highway Expansion
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Agricultural
Property
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Landfill
Cleanup
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Schools
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Battery
Plants
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Metal-working Facilities
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Former oil well property
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Using
“grab sample” methods alone, the XRF is capable of reliably guiding
the excavation for cleanup of lead concentrations as
low as 30 mg/kg (ppm).
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ACCURACY: Accuracy is increased as the homogeneity of the sample is
increased and homogeneity is improved by additional field preparation.
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COMPARING XRF TO LAB ANALYSIS: Our experience has shown
that samples that have been dried, then field-prepped though a standard
2.00 mm, # 10 mesh sieve followed by a standard # 25 mesh sieve should
have an XRF test result that is within +/-
15% of the laboratory analysis
of the SAME sample.
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THE
ADVANTAGES OF FIELD SCREENING WITH XRF:
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Reduce
Disposal and Treatment Costs. Limit the volume of soil that
will require disposal and treatment by only excavating where
contamination exists.
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Eliminate
Failed Clearances. Collect, prepare and analyze clearance samples
on-site. Because the XRF testing is non-destructive, you can
send the same samples to the lab for confirmation after clearance
criteria are met.
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Guide
the Investigation. Due to the
“real time” result capability of the XRF, sampling plans can be
modified in the field as the excavation proceeds. Find out today where
you need to do your "step-outs" - not days later.
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Cost
Effective. The per-sample analytical costs are comparable to the
standard laboratory method with a two-week turn-around time, yet the
XRF results are available within minutes. With XRF Field Screening,
field operation delays are reduced and continuous excavation can be
conducted without incurring additional mobilization/demobilization
costs. The XRF allows you
to eliminate the unnecessary sampling that can occur with pre-determined
sampling plans. And, site security and
dust suppression costs are also minimized due to quicker completion of
the corrective action activities.
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Fast.
The XRF analysis of a soil sample can be completed in approximately 2
to 10 minutes after the sample is prepared. The length of time for the
sample analysis is dependent upon the desired accuracy and the
"cleanup level", i.e., lower cleanup
levels require longer analysis time.
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QUALITY
ASSURANCE METHODS
The
Field Screening methods utilized provide basic quality assurance,
including calibration verification, determination of instrument precision,
accuracy and limit of detection.
Quality assurance methods can be divided into three main
areas:
1.
ENSURING THAT CLEARANCE CRITERIA OBJECTIVES ARE CLEAR
Understanding
our Clients' Clearance Levels. Duration of sampling times are increased or
decreased in direct proportion to clearance criteria. (e.g., the lower the
lead or metal "clean-up" concentration the longer the sample
duration will need to be to achieve desired accuracy.)
2.
CALIBRATION CHECKS TO ENSURE CORRECT INSTRUMENT OPERATION
Quality
assurance constitutes testing of known Standards to verify that
calibration is within acceptable parameters as well as testing blank
Standards to determine limits of detection.
3. SAMPLE
PREPARATION PROTOCOL
Moisture
and soil particle size effects are minimized by a sample preparation
protocol that includes:
- Drying
the sample.
- Exclusion
of particles larger than 2.00 mm.
- Using
low-bias methods for sample splitting.
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Gray Environmental, Inc.
regularly performs projects where a representative number of XRF
field-screened soil samples are submitted by the client to laboratories for lead analysis.
EPA Method 6010B for
metals is typically performed in the laboratory. The following table presents
the complete data set of confirmatory
sampling from two selected projects.
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TABLE 1, Confidential
Client, San Diego.
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Sample Number
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- Results by XRF
- (mg/kg)
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- Results by EPA Method 6010B Laboratory
- Analysis
- (mg/kg)
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- Accuracy Relative to
the Action Level of 20 mg/kg
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| A1-101 |
102 |
133 |
Correct |
| A1-104 |
35 |
64 |
Correct |
| A1-112 |
2.0 |
1.89 |
Correct |
| A1-119 |
26.3 |
45.1 |
Correct |
| A1-WE-1.5 |
184 |
99 |
Correct |
| A1-WN-0.5 |
22.5 |
24.6 |
Correct |
| A2-103 |
251 |
245 |
Correct |
| A2-105 |
154 |
114 |
Correct |
| A2-116 |
84 |
64.5 |
Correct |
| A2-118 |
<20 |
26.5 |
False negative |
| B2-CON8WE1 |
104 |
97.4 |
Correct |
| B4-100 |
74.8 |
136 |
Correct |
| B4-106 |
<20 |
2.8 |
Correct |
| B4-111 |
34.5 |
6.9 |
False positive |
| C-109 |
56,100 |
52,500 |
Correct |
| C1-106 |
60.8 |
91.9 |
Correct |
| C1-109 |
185 |
172 |
Correct |
| C1-110 |
<20 |
7.35 |
Correct |
| D1-104 |
12.3 |
16.5 |
Correct |
| D1-113 |
91.3 |
43.6 |
Correct |
| D1-114 |
418 |
558 |
Correct |
| D2-100 |
<20 |
15.5 |
Correct |
| D2-106 |
105 |
93.5 |
Correct |
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TABLE 2, Confidential
Client, Los Angeles. |
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Sample Number
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- Results by XRF
- (mg/kg)
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- Results by EPA Method 6010B Laboratory
- Analysis
- (mg/kg)
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Accuracy Relative to
the Action Level of 255 mg/kg |
| SS-4-0.5' |
665.6 |
623 |
Correct |
| SS-20-0.5' |
497.2 |
446 |
Correct |
| SS-19-0.5' |
583.2 |
526 |
Correct |
| SS-5-0.5' |
285.4 |
232 |
False
Positive |
| SS-9-0.5' |
766 |
571 |
Correct |
| SS-8-0.5' |
644.4 |
585 |
Correct |
| SS-18-0.5' |
424.8 |
356 |
Correct |
| SS-7-0.5' |
509.6 |
443 |
Correct |
| SS-15-0.5' |
886.4 |
738 |
Correct |
| SS-17-0.5' |
205 |
131 |
Correct |
| SS-16-0.5' |
959.2 |
801 |
Correct |
| SS-24-0.5' |
201 |
158 |
Correct |
| SS-6-0.5' |
708.8 |
618 |
Correct |
| SS-26-0.5' |
426.4 |
353 |
Correct |
| SS-28-0.5 |
1349.6 |
1010 |
Correct |
| SS-25-0.5' |
470.8 |
416 |
Correct |
| SS-31-0.5' |
402.6 |
332 |
Correct |
| SS-25-1.5' |
212.6 |
176 |
Correct |
| SS-31
B-0.5' |
353 |
308 |
Correct |
| SS-31-1.5' |
272.6 |
284 |
Correct |
| SS-34-0.5 |
690.8 |
699 |
Correct |
| SS-33-0.5' |
832 |
817 |
Correct |
| SS-36-0.5 |
516.4 |
492 |
Correct |
| SS-37-0.5' |
557.6 |
528 |
Correct |
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(i.e., Mobilization to Other
States)
Gray Environmental, Inc. has the
capability to
perform XRF soil testing in other states.
Advance Project
Notice Required
Call or email us
for details (see below for email address)
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Or give us a call:
San
Diego, California - (760)
842-5948
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- Copyright © 1999-2007. All Rights Reserved.
- Gray Environmental, Inc.
- Last Revised: October 15, 2007
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